The challenge to meet the ever increasing demand for oil includes increasing crude oil recovery from heavy oil reservoirs. This challenge has resulted in expanding efforts to develop alternative cost efficient oil recovery processes (Kianipey, S. A. and Donaldson, E. C. 61st Annual Technical Conference and Exhibition, New Orleans, La., USA, Oct. 5-8, 1986). Heavy hydrocarbons in the form of petroleum deposits and oil reservoirs are distributed worldwide. These oil reserves are measured in the hundreds of billions of recoverable barrels. Because heavy crude oil has a relatively high viscosity, it is essentially immobile and cannot be easily recovered by conventional primary and secondary means.
Microbial Enhanced Oil Recovery (MEOR) is a methodology for increasing oil recovery by the action of microorganisms (Brown, L. R., Vadie, A. A,. Stephen, O. J. SPE 59306, SPE/DOE Improved Oil Recovery Symposium, Oklahoma, 3-5—Apr., 2000). MEOR research and development is an ongoing effort directed to developing techniques to use microorganisms to modify crude oil properties to benefit oil recovery (Sunde. E., Beeder, J., Nilsen, R. K. Torsvik, T., SPE 24204, SPE/DOE 8th Symposium on enhanced Oil Recovery, Tulsa, Okla., USA, Apr. 22-24, 1992).
Methods for identifying microorganisms useful in MEOR processes have been described. These methods require identification of samples drawn from an oil well or reservoir comprising a consortium of microorganisms and enrichment or evolution of populations in the sample, under specific conditions with defined nutrient media. See, U.S. patent application Ser. No. 10/564,365.
Microbial degradation of hydrocarbons has also been described, under aerobic or mixed (aerobe and anaerobic) conditions, as a mechanism for oil viscosity reduction. Degradation under these circumstances requires evolved microorganisms and particular nutrients which have not been demonstrated as an economic means for improving oil recovery (See, U.S. Pat. No. 5,492,828).
Thus, there is a need for developing methods to: 1) identify microorganisms that could be used to enhance oil recovery under economic conditions; 2) identify microorganisms that can grow on oil under anaerobic conditions without the need for nutrient supplementation or long term enrichment of indigenous microorganisms; and 3) use said identified microorganisms, in a cost-efficient way, to improve oil recovery.